This invention relates to insulated glass assemblies. In particular, it relates to a composite spacer for use in an insulated glass assembly and further relates to an insulated glass assembly incorporating such a spacer.
Insulated glass assemblies presently known in the art incorporate the use of various polymeric substances in combination with other materials. One such assembly includes a butylated polymer in which there is embedded an undulating metal spacer. Although useful, this type of sealant strip is limited in that the metal spacer, over time, becomes exposed to the substrates which results in a drastic depreciation in the efficiency of the strip. The particular difficulty arises with moisture vapour transmission when the spacer becomes exposed and contacts the substrates.
Further, many of the butylated polymers currently used in insulated glass assemblies are impregnated with a desiccant.
This results in a further problem, namely decreased adhesiveness of the butylated sealant.
Glover, et al. in U.S. Pat. No. 4,950,344, provide a spacer assembly including a foam body separated by a vapour barrier and further including a sealant means about the periphery of the assembly. Although this arrangement is particularly efficient from an energy point of view, one of the key limitations is that the assembly must be fabricated in a number of steps. Generally speaking, the sealant must be gunned about the periphery in a subsequent step to the initial placement of the spacer. This has ramifications during the manufacturing phase and is directly related to increased production costs and, therefore, increased costs in the assembly itself.
It has been found particularly advantageous to incorporate, as a major component of the spacer, a soft, resilient insulated body, having a low thermal conductivity. Examples of materials found to be useful include natural and synthetic elastomers (rubber), cork, EPDM, silicones, polyurethanes and foamed polysilicones, urethanes and other suitable foamed materials. Significant benefits arise from the choice of these materials since not only are they excellent insulators from an energy point of view but additionally, depending on the materials used, the entire spacer can maintain a certain degree of resiliency. This is important where windows, for example, engaged with such a strip experience fluctuating pressure forces as well as a thermal contraction and expansion. By making use of a resilient body, these stresses are alleviated and accordingly, the stress is not transferred to the substrates as would be the case, for example, in assemblies incorporating rigid spacers. However, an overly resilient spacer will tend to flex sideways, twist or compress either during the assembly process or subsequently when the insulated assembly is stressed.
Effective insulating spacers may achieve their effectiveness by trapping a volume of dead air. For example, the spacer body may comprise a thermal plastic or thermal setting foam material. However, conventional foam materials are typically relatively soft and may not be sufficiently rigid for use in association with insulating glass units. As well, a foam spacer formed essentially of a strip of foam material, having a rectangular cross-section, will tend to buckle at the spacer corners. Spacer buckling may be addressed either by rounding off the corners, which presents functional and aesthetic drawbacks, or by slitting and backfilling of the corners. The latter approach, while effective, requires a number of steps and may be relatively costly. Thus, there is a need for an insulating spacer material which has a degree of rigidity, readily forms sharp corners, and is relatively inexpensive and simple to fabricate and apply. Desirably, such a material traps a volume of dead air therein to achieve a superior level of insulation.
It would be desirable to have a composite spacer which overcomes the limitations of desiccated butyl as well as requiring the addition of sealant material in a subsequent procedure. The present invention is directed to satisfying the limitations in the known art.
The term xe2x80x9cglassxe2x80x9d herein also embraces plastics such as Plexiglass (tm) and the like.
An object of the present invention is to provide an improved spacer for use in insulated glass or glazing assemblies, the spacer incorporating a volume of dead air or other gas to achieve superior insulating qualities. A further object is to provide an improved insulated glass assembly incorporating such a spacer. A further object is to provide an improved spacer which is an effective insulator, while being relatively simple and inexpensive to manufacture and apply. A further object is to provide an insulating spacer which is relatively rigid and resists twisting and bending forces.
In accordance with the above objects, in one aspect the invention comprises a composite spacer for spacing substrates in an insulated glass assembly. The spacer comprises: an insulating spacer core having upper and lower flat substrate engaging surfaces, a front face for facing into the interior of said insulated glass assembly, and a rear face spaced apart from said front face. The spacer core comprises a generally linear array of cellular members. The rear face of the core is characterized by a regular array of deep indentations which define the individual members. In one version, the indentations are rounded to form a sinusoidal or undulating rear face. Alternatively, the members may be triangular or rectangular in cross-section. Preferably, the members each comprise a hollow, gas-filled chamber. In this version, the interior of said spacer core comprises an essentially linear array of hollow cells for trapping dead air therein, wherein said semi-cylindrical members each define a single cell. Conveniently, the spacer body is formed from blow moulded plastic such as PVC or vinyl.
In another aspect, both of the front and rear faces of the spacer core undulate to form an essentially linear array of generally cylindrical members, each of which defines a hollow cell or chamber.
In another aspect, a composite spacer is provided in which the rear face of the above spacer core is covered by a sealant material such as silicone or hot melt. In a further aspect, the substrate engaging surfaces of the spacer body are both covered with a sealant material such as a hot melt material. The front face preferably incorporates one or more of a vapour barrier film and a desiccant.
In another aspect, a composite spacer core comprises a pair of spacer cores in face to face relation, surrounded by hot melt or other flowable substrate to bind them together. For example, the spacer cover may each comprise an array of triangular members which interfinger when placed in face to face relationship.
In a further aspect, a clip is provided to hold neighboring spacer core cellular members in angled disposition to each other where the spacer extends around a corner.
The spacer core may be formed in a fully extruded fashion partly or fully surrounded by hot melt, Swizzle (TM) or other matrix. Alternatively, the spacer core may be co-extruded with one or more matrices such as desiccant, hot melt or other backing.
Preferably, the spacer core is formed from blow moulded PVC or vinyl, to form an essentially linear array of hollow cells or chambers, each cell having an outside sidewall being defined by an undulation of the spacer body.
The advantages achieved by a structure, include relatively high resistance to compressive forces as a result of the rigidity of the structure. As well, twisting and sideways bending of the spacer is minimized as a result of the spacer""s relative rigidity. Preferably, the width of the spacer is sufficiently wide to minimize twisting and bending. As well, the undulations permit the spacer to form relatively sharp corners without slitting.
Suitable sealants include polyisobutylene (PIB) butyl or other butylated material which extends about the periphery of the assembly or at least on the flat substrate engaging surfaces of the spacer core and thereby provides a further sealed surface. Sealing or other adhesion for the insulating body may be achieved by providing special adhesives such as acrylic adhesive at the substrate engaging surfaces. Further, the material at the substrate engaging surfaces may be uncured so that on application of heat, the body adheres directly to the substrate. This is effective where there is provided at the substrate engaging surfaces a material composed of, for example, a ultra violet curable material.
The spacer may comprise a composite structure which includes as an integral component a desiccant matrix and/or vapour barrier film, on the front face of the spacer body. The desiccant material may be in the form of a matrix of a semi-permeable material. Various silicones with desiccant material disbursed therein are known to the art. Alternatively, where a separate matrix is not incorporated, a sealant material on the front face may include a desiccant material. Adhesive layers on the upper and lower faces permit the spacer to be mounted to substrates such as glass to form an IG unit.
In a further aspect, the invention comprises an insulating assembly, comprising spaced apart glass or plastic substrates, with a spacer of the type described above extending around the periphery of the assembly. A further layer of sealant material may be provided around the periphery of the assembly in contact with all or part of the rear face of the spacer.